1. Field of the Invention
The present invention relates generally to methods for achieving improved pesticidal efficacy in treatment of arthropods. More particularly, the methods of the present invention comprise depositing drops of pesticidal formulations containing at least one surfactant on the surface of treated arthropods to cause enhanced knockdown (KD) effects on the arthropods as a result of the contact angles presented by the drops relative to the surface.
2. Description of Related Art
Pesticidal formulations can be in the form of solutions, emulsions, suspensions, dispersions and the like, and are used in agriculture for applying agricultural chemicals to plants, soil, insects and the like. Among typical pesticidal chemicals are herbicides, insecticides, fungicides, growth regulators and the like.
Such formulations have been known to contain surfactants such as trisiloxane surfactants and other surfactants to enhance the physical characteristics of the formulation for treating pests. For example, in U.S. Pat. No. 6,734,141 (“the '141 patent”) and in an article by Cowles et al, entitled “Trisiloxane Surfactant Solutions are Miticidal” which was published in the April, 2000 edition of The Journal of Economic Entomolgy, Vol. 93, no. 2 (“the Cowles et al article”), the use of silicone surfactants, including siloxane surfactants, in agrochemical pesticidal formulations was described.
However, prior pesticidal formulations including those employing surfactants therein such as the formulations described in the '141 patent and in the Cowles et al article have not been sufficiently effective for causing rapid knockdown (KD) of arthropods treated therewith. For example, it has been found that the use of surfactants such as silicone surfactants in agricultural formulations have been only partially effective in causing rapid “knockdown” (KD) of treated arthropods and have been commercially ineffective in causing enhanced knockdown (KD) effects, particularly, in regard to difficult to control pests such as cockroaches.
As employed herein, the expression “enhanced knockdown (KD) effects” refers to the rapid knockdown (KD) of treated arthropods wherein the term “rapid knockdown (KD)” means within a period two (2) minutes or less from the time that at least one drop of the pesticidal formulation is deposited on the surface of an arthropod in which to achieve disruption of mobility of the treated arthropod which normally will lead to mortality of such treated arthropod.
The term arthropod as employed herein means any invertebrate of the phylum Arthropoda including insects, spiders and other arachnids, crustaceans, myriapods and various household pests. For purposes hereof, cockroaches are specifically to be considered to fall within the definition of arthropods.
The deficiency in speed of KD achieved with prior art pesticidal formulations is significant and there has been an on-going need in the consumer market for liquid insecticidal ready-to-use products, which provide fast and effective KD rates of treated arthropods leading to relatively quick mortality (i.e., death) of the treated arthropods.
For example, known formulations often require as much as one-quarter hour or more to achieve acceptable KD rates leading to desired mortality levels against difficult to control pests, such as American cockroaches (Periplaneta americana).
Thus, it has been recognized heretofore that it would be advantageous to provide formulations and methods for achieving rapid knockdown of treated arthropods, preferably, resulting in quick kill of the treated arthropods including such difficult to control pests as cockroaches.
For example, it has been recognized that it would be highly beneficial to provide compositions that would achieve KD rates in the order of 80% or greater within about 2 minutes or less and, preferably, within 60 seconds or less, after treatment of the arthropods.
In our copending U.S. patent application Ser. No. 11/801,441, filed May 10, 2007, pesticidal formulations are described that contain surfactants which enable the formulation to have a dynamic surface tension as measured with a Krüss Bubble Pressure Tensiometer (BP2 Version 1.20) which provides enhanced mortality rates (quick kill) of arthropods treated with the formulations.
Furthermore, in our copending U.S. patent application Ser. No. 11/801,466, filed May 10, 2007, silicone surfactant-based agricultural formulations are described containing combinations of silicone surfactants at concentrations sufficient to cause synergistically quick knockdown (KD) levels on treated arthropods.
Nonetheless, it has been found that it would be highly desirable to provide new and improved methods for achieving improved pesticidal effects when formulations containing surfactants such as those disclosed in our above referenced copending applications are deposited on the surface of a treated arthropod such as a cockroach.
In particular, it would be advantageous to provide methods for more effectively employing formulations which contain surfactants, such as certain trisiloxane surfactants and suitable other surfactants, which act to reduce the contact angle of the formulation to a level which enables an effective knockdown (KD) rate within about two minutes or less after the formulation is deposited on a surface of a treated arthropod.
Additionally, it would be advantageous to provide methods for more effectively employing agricultural formulations which contain surfactants, such as certain trisiloxane surfactants and suitable other surfactants, to achieve enhanced knockdown rates, preferably, about 80% or greater, within shorter periods of time when applied to arthropods and particularly to difficult to control arthropods such as cockroaches.